To use the interactive tool, go to the bottom of the problem and press download. It'll warn you about the program, but (for chrome) just go to chrome://downloads/ and click allow. From there, use their instructions: C++, after compilation: python testing_tool.py ./my_binary Python: python testing_tool.py python my_code.py Java, after compilation: python testing_tool.py java my_main_class_name If you can't download it, copy and paste this and put it into a file called testing_tool.py: https://hastebin.com/ayalutugad.py